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- markus@cvs.openbsd.org 2001/12/19 16:09:39
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8efc0c15 1/*
5260325f 2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5260325f 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5260325f 5 * Auxiliary functions for storing and retrieving various data types to/from
6 * Buffers.
7 *
bcbf86ec 8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 *
14 *
7368a6c8 15 * SSH2 packet format added by Markus Friedl
bcbf86ec 16 * Copyright (c) 2000 Markus Friedl. All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
7368a6c8 26 *
bcbf86ec 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
5260325f 37 */
8efc0c15 38
39#include "includes.h"
184eed6a 40RCSID("$OpenBSD: bufaux.c,v 1.19 2001/12/19 07:18:56 deraadt Exp $");
8efc0c15 41
8efc0c15 42#include <openssl/bn.h>
43#include "bufaux.h"
44#include "xmalloc.h"
45#include "getput.h"
42f11eb2 46#include "log.h"
8efc0c15 47
5260325f 48/*
49 * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
50 * by (bits+7)/8 bytes of binary data, msb first.
51 */
8efc0c15 52void
53buffer_put_bignum(Buffer *buffer, BIGNUM *value)
54{
5260325f 55 int bits = BN_num_bits(value);
56 int bin_size = (bits + 7) / 8;
1e3b8b07 57 u_char *buf = xmalloc(bin_size);
5260325f 58 int oi;
59 char msg[2];
60
61 /* Get the value of in binary */
62 oi = BN_bn2bin(value, buf);
63 if (oi != bin_size)
64 fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
184eed6a 65 oi, bin_size);
5260325f 66
67 /* Store the number of bits in the buffer in two bytes, msb first. */
68 PUT_16BIT(msg, bits);
69 buffer_append(buffer, msg, 2);
70 /* Store the binary data. */
610cd5c6 71 buffer_append(buffer, (char *)buf, oi);
aa3378df 72
5260325f 73 memset(buf, 0, bin_size);
74 xfree(buf);
8efc0c15 75}
76
5260325f 77/*
78 * Retrieves an BIGNUM from the buffer.
79 */
8efc0c15 80int
81buffer_get_bignum(Buffer *buffer, BIGNUM *value)
82{
5260325f 83 int bits, bytes;
1e3b8b07 84 u_char buf[2], *bin;
5260325f 85
86 /* Get the number for bits. */
87 buffer_get(buffer, (char *) buf, 2);
88 bits = GET_16BIT(buf);
89 /* Compute the number of binary bytes that follow. */
90 bytes = (bits + 7) / 8;
91 if (buffer_len(buffer) < bytes)
92 fatal("buffer_get_bignum: input buffer too small");
b5c334cc 93 bin = (u_char *) buffer_ptr(buffer);
5260325f 94 BN_bin2bn(bin, bytes, value);
95 buffer_consume(buffer, bytes);
96
97 return 2 + bytes;
8efc0c15 98}
99
7368a6c8 100/*
101 * Stores an BIGNUM in the buffer in SSH2 format.
102 */
103void
104buffer_put_bignum2(Buffer *buffer, BIGNUM *value)
105{
106 int bytes = BN_num_bytes(value) + 1;
1e3b8b07 107 u_char *buf = xmalloc(bytes);
7368a6c8 108 int oi;
109 int hasnohigh = 0;
110 buf[0] = '\0';
111 /* Get the value of in binary */
112 oi = BN_bn2bin(value, buf+1);
113 if (oi != bytes-1)
114 fatal("buffer_put_bignum: BN_bn2bin() failed: oi %d != bin_size %d",
184eed6a 115 oi, bytes);
7368a6c8 116 hasnohigh = (buf[1] & 0x80) ? 0 : 1;
117 if (value->neg) {
118 /**XXX should be two's-complement */
119 int i, carry;
1e3b8b07 120 u_char *uc = buf;
7368a6c8 121 log("negativ!");
184eed6a 122 for (i = bytes-1, carry = 1; i>=0; i--) {
7368a6c8 123 uc[i] ^= 0xff;
6aacefa7 124 if (carry)
7368a6c8 125 carry = !++uc[i];
126 }
127 }
128 buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
129 memset(buf, 0, bytes);
130 xfree(buf);
131}
132
133int
134buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
135{
136 /**XXX should be two's-complement */
137 int len;
1e3b8b07 138 u_char *bin = (u_char *)buffer_get_string(buffer, (u_int *)&len);
7368a6c8 139 BN_bin2bn(bin, len, value);
140 xfree(bin);
141 return len;
142}
143
5260325f 144/*
145 * Returns an integer from the buffer (4 bytes, msb first).
146 */
1e3b8b07 147u_int
5260325f 148buffer_get_int(Buffer *buffer)
8efc0c15 149{
1e3b8b07 150 u_char buf[4];
5260325f 151 buffer_get(buffer, (char *) buf, 4);
152 return GET_32BIT(buf);
8efc0c15 153}
154
afecff1d 155#ifdef HAVE_U_INT64_T
f546c780 156u_int64_t
157buffer_get_int64(Buffer *buffer)
158{
159 u_char buf[8];
160 buffer_get(buffer, (char *) buf, 8);
161 return GET_64BIT(buf);
162}
afecff1d 163#endif
f546c780 164
5260325f 165/*
166 * Stores an integer in the buffer in 4 bytes, msb first.
167 */
35484284 168void
1e3b8b07 169buffer_put_int(Buffer *buffer, u_int value)
8efc0c15 170{
5260325f 171 char buf[4];
172 PUT_32BIT(buf, value);
173 buffer_append(buffer, buf, 4);
8efc0c15 174}
175
afecff1d 176#ifdef HAVE_U_INT64_T
f546c780 177void
178buffer_put_int64(Buffer *buffer, u_int64_t value)
179{
180 char buf[8];
181 PUT_64BIT(buf, value);
182 buffer_append(buffer, buf, 8);
183}
afecff1d 184#endif
f546c780 185
5260325f 186/*
187 * Returns an arbitrary binary string from the buffer. The string cannot
188 * be longer than 256k. The returned value points to memory allocated
189 * with xmalloc; it is the responsibility of the calling function to free
190 * the data. If length_ptr is non-NULL, the length of the returned data
191 * will be stored there. A null character will be automatically appended
192 * to the returned string, and is not counted in length.
193 */
194char *
1e3b8b07 195buffer_get_string(Buffer *buffer, u_int *length_ptr)
8efc0c15 196{
1e3b8b07 197 u_int len;
5260325f 198 char *value;
199 /* Get the length. */
200 len = buffer_get_int(buffer);
201 if (len > 256 * 1024)
202 fatal("Received packet with bad string length %d", len);
203 /* Allocate space for the string. Add one byte for a null character. */
204 value = xmalloc(len + 1);
205 /* Get the string. */
206 buffer_get(buffer, value, len);
207 /* Append a null character to make processing easier. */
208 value[len] = 0;
209 /* Optionally return the length of the string. */
210 if (length_ptr)
211 *length_ptr = len;
212 return value;
8efc0c15 213}
214
5260325f 215/*
216 * Stores and arbitrary binary string in the buffer.
217 */
35484284 218void
1e3b8b07 219buffer_put_string(Buffer *buffer, const void *buf, u_int len)
8efc0c15 220{
5260325f 221 buffer_put_int(buffer, len);
222 buffer_append(buffer, buf, len);
8efc0c15 223}
35484284 224void
7368a6c8 225buffer_put_cstring(Buffer *buffer, const char *s)
226{
227 buffer_put_string(buffer, s, strlen(s));
228}
8efc0c15 229
5260325f 230/*
231 * Returns a character from the buffer (0 - 255).
232 */
35484284 233int
5260325f 234buffer_get_char(Buffer *buffer)
8efc0c15 235{
5260325f 236 char ch;
237 buffer_get(buffer, &ch, 1);
1e3b8b07 238 return (u_char) ch;
8efc0c15 239}
240
5260325f 241/*
242 * Stores a character in the buffer.
243 */
35484284 244void
5260325f 245buffer_put_char(Buffer *buffer, int value)
8efc0c15 246{
5260325f 247 char ch = value;
248 buffer_append(buffer, &ch, 1);
8efc0c15 249}
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